Electric double-layer screening, molecular

M. R. Philpott, J. N. Glosli. Molecular dynamics simulation of interfacial electrochemical processes electric double layer screening. In G. Jerkiewicz, M. P. Soriaga, K. Uosaki, A. Wieckowski, eds. Solid Liquid Electrochemical Interfaces, Vol. 656 of ACS Symposium Series. Washington ACS, 1997, Chap. 2, pp. 13-30. 

Philpott MR, GlosU JN (1997) Molecular dynamics simulation of interfadal electrochemical processes electric double layer screening. In Jerkiewicz G, Soriaga MP, Uosaki K, Wieckowski A (eds) Solid-liquid electrochemical interfaces. American Chemical Society, Washington... 

Molecular Dynamics Simulation of Interfacial Electrochemical Processes Electric Double Layer Screening... 

In an electrochemical context, the situation is somewhat simplified since the value of Ef for an electrode surface can be controlled (with the aid of a stable reference electrode and an electrical double layer, which serves to screen electrons that reside in the electrode such that the energy level of a molecular orbital in solution is not impacted by the applied potential). Thus, in electrochemical studies, the value of 4> can be reduced to zero, enabling electrons to be removed from the HOMO orbital of solution-based molecules (oxidation), or to be added to the LUMO orbital (reduction). However, in the context of a solid-state molecular electronic junction, the value of a nonresonant interfacial barrier remains essentially static at different voltages. We discuss some of the reasons in more detail below that it cannot be assumed that their energy levels in a completed junction are set by the properties of the individual, isolated components. In any case, the presence of an interfacial barrier in a solid-state junction is a critical parameter in determining the electron transport properties of the device, regardless of the specific mechanism in operation. Thus, the appearance of Figure 10.12 needs to be taken in the context of the specific mechanism(s) under study. 

The status of computer simulations of electric double layers is briefly summarized and a road map for solving the important problems in the atomic scale simulation of interfacial electrochemical processes is proposed. As examples efforts to simulate screening in electric double layers are described. Molecular dynamics simulations on systems about 4 nm thick, containing up to 1600 water molecules and NaQ at IM to 3M concentration, displayed the main features of double layers at charged metal surfaces including bulk electrolyte zone, diffuse ionic layer that screens the charge on the electrode and a layer of oriented water next to the surface. 

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